A vehicle occupant restraint system may include a sensor for providing a position signal indicative of the position of a vehicle occupant in a vehicle seat. The position signal is then processed to provide a control signal to control an actuatable safety device depending upon the position of the vehicle occupant in the vehicle seat. For example, an occupant position sensor may be used in an inflatable restraint system to control inflation of an air bag depending upon the position of a vehicle occupant in a vehicle seat.
Typically, an occupant position sensor is mounted in front of the vehicle occupant, such as on the vehicle instrument panel, or to the side of the occupant. Mounting an occupant position sensor in front of a vehicle occupant or to the side of the occupant may provide a false reading because of an object placed between the position sensor and the occupant. For example, the object may be the hand of the vehicle occupant, the crossed legs of the occupant, or a map or the like held between the position sensor and the occupant.
U.S. Pat. No. 5,118,134 suggests mounting a position sensor in the head rest of a vehicle seat. However, a position sensor mounted in the head rest may not be able to sense the position of a relatively short occupant seated in the vehicle seat.